I want on honest answer in relation to this question, not so I can criticise you but to understand your logic behind this.
Let's say as an example based on what you say - tax increases per cc size of the engine based on 0.1 increments, so -
<1.0cc - free road tax
<1.1cc - £20
<1.2cc - £40
<1.3cc - £60
<1.4cc - £80
<1.5cc - £100
List can carry on with the assumption obviously that the biggest engines get charged a hell of a lot more.
Let's say this starts straight away and affects every single car on the road.
Take your own car, a modest supermini with a low powered underperforming 1.4 engine with a pedestrian 77bhp doing 60 in 12.8 seconds with a quoted c02 of 134 and 49mph - by the table I constructed above you will need to pay £80 a year to tax it.
In comparison let's take a Fiesta 1.0 black/red edition. This has a modest sized 1.0 engine, but this produced 138bhp it does a claimed 60mph in 8.7 seconds, 104 co2, and returns 62mpg - this will be completely free to tax.
I now want you to explain why you would happy with your Punto to be paying road tax of £80 when it offers no where near the performance, emissions or MPG of the example given?
Would this be fair to you?